1. Field of the Invention
The present invention relates to an organopolysiloxane composition and a semiconductor apparatus, in particular, an organopolysiloxane composition that provides a cured product capable of sealing a semiconductor device without peeling or cracking even under high temperatures, and a semiconductor apparatus using the composition.
2. Description of the Related Art
Accompanying the evolution of industrial machinery, electric trains, automobiles, and the like, the temperatures at which a semiconductor device in any such machine is used have been increasing. In particular, semiconductor devices that operate even under temperatures as high as 175° C. or more have been vigorously developed in recent years. In addition to the aforementioned, the reduction of semiconductor device size and the increase in the withstand voltages and current densities of semiconductor devices have also been advanced. For example, compound semiconductors such as SiC and GaN each have a larger band gap than that of an Si semiconductor. Accordingly, an increase in withstand voltage of the device, a reduction in the size of the device, an increase in current density of the device, and an increase in temperature at which the device operates is expected of the use of any such compound as a semiconductor.
In order that semiconductor devices having such characteristics as described above may be used on a semiconductor apparatus, the insulating property of a circuit must be secured by sealing the semiconductor device with an insulating material that does not thermally decomposing even over long time period even under temperatures as high as 175° C. or more. In view of the aforementioned, a method involving sealing the semiconductor device with a cured product of an organopolysiloxane composition which has excellent heat resistance has been proposed (see, for example, Japanese Patent Application Laid-open No. 2006-73950).
However, in the method involving sealing the semiconductor device with the cured product of the organopolysiloxane composition described in Japanese Patent Application Laid-open No. 2006-73950, when the temperature of the semiconductor device increases so that the periphery of the semiconductor device may be locally heated, thermal stress occurring in the cured product increases locally in some cases. As a result, peeling or cracking of the cured product occurs and as a consequence of this the insulating property of the semiconductor apparatus is remarkably reduced.
Until now, it has been generally considered that an increase in crosslinking (that is, branched structures) of the cured product is sufficient to improve the adhesiveness of the cured product to the semiconductor device. However, as such cured product is hard and brittle, the occurrence of thermal stress leads to the peeling or cracking of the cured product. As a result, the insulating properties of the semiconductor apparatus are lost.